I've tried to realise the following circuit:
http://www.elecdesign.com/Files/29/3168/Figure_01.gif
from this article:
http://www.elecdesign.com/Articles/Index.cfm?AD=1&ArticleID=3168
to demod a QPSK signal. I've tried using an AD8347 (Evaluation Board),
but
i'm not able to retrieve the "terms at twice the rate of the oscillator".
All I can get from the outputs are the difference between the RF and LO,
both I and Q.
I'm using an (tunable) RF at 1.44GHz and LO at the same frequency. The LO
is
generated by ADF411xEB1. Even when I try to tune the RF as close to the
LO,
the "terms at twice the rate of the oscillator" never appears.
Is this becaues the range of AD8347 is 0.8-2.7GHz? So the doubler term,
2.88GHz, can never appear?
Has anyone tried any other components to realise this circuit?
Thanx in advance!
kw
